NAME

acosh, acoshf, acoshl — inverse hyperbolic cosine function

LIBRARY

Math Library (libm, -lm)

SYNOPSIS

#include <math.h>

double
acosh(double x);

float
acoshf(float x);

long double
acoshl(long double x);

DESCRIPTION

The acosh(), acoshf(), and acoshl() functions compute the inverse hyperbolic cosine of the real argument x.

RETURN VALUES

If x is less than one, acosh(x), acoshf(x), and acoshl(x) return NaN and set the global variable errno to EDOM.

SEE ALSO

asinh(3), atanh(3), exp(3), math(3)

STANDARDS

The acosh() function conforms to ISO/IEC 9899:1999 (“ISO C99”).

HISTORY

The acosh() function appeared in 4.3BSD.